There are millions of SCBA users in the United States alone, including firefighters, rescue workers, and hazardous materials workers. SCBAs are worn in hazardous environments over 100 million times each year. SCBAs provide clean breathing air on demand and maintain a positive pressure in the facepiece, protecting the user from toxic gases and aerosols in the environment.
Prior art SCBA regulators can be slow to respond to very rapid breathing transients. As a result, there is a potential to “over breathe” the regulator, which reduces the facepiece pressure below the ambient pressure and potentially allows toxic gases to leak in from the environment.
Another shortcoming of prior art regulators results from the fact that many use a purely mechanical design. Purely mechanical designs may cause a number of dynamic stability issues under certain conditions. As a result, it is often difficult to set the nominal static facepiece pressure, i.e., exhalation pressure, to a low value. Conventional SCBAs have a nominal exhale pressure of approximately 2 or 3 inches of water pressure over the ambient. The relatively large exhalation pressure is typically very noticeable to a wearer and adds to the breathing work.